The Committee for the Preservation of the White House yesterday began a $20-million fund-raising drive to build an endowment to buy paintings and furnishings.

This is the first time the White House has gone public to pay for redecoration. Until now, money has been raised quietly from among wealthy donors. The only money from the public has come from the sale of White House guide books and royalties from the Franklin Mint's first lady and presidential medals.

At the same time, the committee was shown some of the $2 million or so of paintings, furniture and memorabilia given to the White House thus far in the Carter admnistration. They included a still-life "Cincinnati Enquirer 1888" by William Michael Harnett, which First Lady Rosalynn Carter said her husband liked so much he asked that it be hung in the west sitting room.

The fund-raising drive will be conducted principally by color brochures mailed to prospective donors suggesting items needed by the White House.

The campaign actually, will be operated by the White House Historical Association according to White House Curator Clement Conger. The association is expected to approve the plan when its board meets in a few days, Conger said. The group traditionally handles money raised from the public, such as in the sale of the White House guide books.

Project plans were announced at the first public meeting yesterday in the White House State Dining Room chaired by Mrs. Carter. Committee member Walter Shorenstein, a San Francisco real estate executive, donated $25,000 seed money to get the campaign underway. Another committee member who was not identified matched that figure.

All committee members were asked to contribute to a list of private and corporate donors to receive the brochure.

Much of the money will go to enlarge the White House's collection of paintings, said Shorenstein, who heads the Preservation committee's finance subcommittes. Conger added that "the White House painting collection is big in quality but not in quantity." Shorenstein also noted the ever-present need to replace fabrics and rugs that wear out because of the 1.5 million visitors to the White House each year.

Conger said the State Department raises from $500,000 to $800,000 for art works and furnishing each year with a similar brochure mailing.

"We hope that it will only be necessary to raise the endowment once, and then the interest should take care of out expenditures," Conger said.

Though Congress appropriates money for the maintenance of the White House, there is no money for acquisitions and there is never enough to cover such things as upholstery and fabric for the walls, Conger pointed ot.

In another development, Conger reported the famous George Washington portrait, saved by Dolley Madison when the White House was burned in 1814, has been sent out ot be cleaned. "It will look better than it has for 10 years. We're removing two coats of years and varnish," he said. In recent years some soubt has been cast as to whether Gilbert Stuart actually painted the portrait. Its conservation may give clues.

Two oval ceiling panels by Constantino Brumidi, who painted most of the murals in the Capitol, were shown to the committee for possible acquisition.

The paintings were orginally installed in the entrance hall ceiling of the White House, but were thrown out by Mrs. Benjamin Harrison in her 1891 redecoration. Conger said the present owners, who "kept them in storage or a barn, wrote the Whtie House and asked if we would like to buy them."

Price of the paintings is $10,000 each with an estimate for conservation of $3,500. Shorenstein promised he would find money to buy them. Conger discussed with the committee the possibility of installing them on the ceiling of the cross-hall, just outside the East Room and the dining room.

Mrs. Carter told the group that she is particularly anxious for the White House to acquire Ameircan Impressionist paintings. "That's Jimmy's and my favorite period," she said. Up until now, the White House has primarily concentrated on paintings, as well as objects of the first third of the 19th century. The Impressionists date from the last third of the 19th century and until about 1920.

Mrs. Carter also said the famous Franklin D. Roosevelt 1938 paino with the "New Deal" eagle legs is being sent back to Steinway to be rebuilt. "None of our guest pianists will, play on it. They say it is tired."

Among the other new acquisitions shown to thecommittee members yesterday was a portrait of Andrew Jackson, painted from life by Ralph Eleaser Whiteside Earl about 1835 and found by Conger in a Charlottesville, Va., antique shop for $4,500. Conger said the painting after cleaning is worth $45,000.

Others include "The Red Mill" by Ernest Lawson, gift of Richard Manoogian; "Florida Sunrise" by martin Johnson Heade, the first painting of a Southern scene to hang in the White House, the gift of Jean Flagler Mathews; a limited edition set of the "Works of Theodore Roosevelt"; seed pearl jewelry once owned by Louisa Catherine Adams, wife of President John Quincy Adams, given by Mrs. Aubrey Evans; a punch bowl of Chinese porcelain famille rose pattern, gift of Mrs. Mitchel Taradash; a pair each of dinner and soup plates from the President James Polk state service; and a sketch of George Washington by Jacques Reich, given by Conger.